1. Field of the Invention
The invention relates in general to a semi-conductor rework process of patterned photo-resist layer, and more particularly to a semi-conductor rework process of the patterned photo-resist layer on a dielectric anti-reflective coating (DARC).
2. Description of the Related Art
Microfilming and etching are two common processes in semi-conductor manufacturing process. After going through sub-processes including dehydration bake, priming, photo-resist spinning, soft bake, exposure, post-exposure bake, development and hard bake, micro-filming process forms a patterned photo-resist layer on the dielectric anti-reflective coating of a substrate to facilitate the subsequent etching process. Moreover, the accuracy and reliability of patterned photo-resist layer has much to do with the results of etching. Therefore, microfilming process really plays an important role in semi-conductor manufacturing process. When patterned photo-resist layer on DARC are found to have defects, e.g., over-etching or remnants on the surface of patterned photo-resist layer, instead of proceeding to etching process, a manufacturer would normally have the patterned photo-resist layer on DARC reworked. The description of the above process is disclosed below with accompanied drawings.
Referring from FIG. 1A to 1D, sectional flowcharts of a conventional semi-conductor rework process of patterned photo-resist layer. In FIG. 1A, first of all, a substrate 12 is provided with dielectric anti-reflective coating (DARC) 14 being formed thereon. Of which, DARC 14, which is made of hydrophilic materials such as SiON or SiO2, can be a SiON layer or can comprise an SiON layer and a SiO2 layer formed thereon. Next, a hexamethyldisilazane (HMDS) layer 16 is formed on DARC 14 through evaporation while the first patterned photo-resist layer 18 is formed on HMDS layer 16 as shown in FIG. 1B. Of which, HMDS layer 16, which is interchangeable with hydrophilic functional groups, an OH or an OOH functional group for instance, facilitates first patterned photo-resist layer 18 to be adhered to DARC 14 firmly. Hence HMDS layer 16 is also called a primer.
If photo-resist manufacturing process needs to be reworked due to a failed micro-filming process or other factors, normally wet strip method or dry strip method is used to remove first patterned photo-resist layer 18 and HMDS layer 16. However, both strip methods always end up with many pin holes on the surface of DARC 14 as shown in FIG. 1C. The wet strip method, first of all, uses an acid agent consisted of HF and H2SO4 to remove first patterned photo-resist layer 18 and HMDS layer 16, wherein the acid agent erodes DARC 14 and leaves many pin holes containing ruminants of acid agent on the surface of DARC 14. Next, the wet strip method washes the surface of DARC 14 using an alkaline agent consisted of NH4OH, H2O2 and de-ionized water to remove the particles adhered thereto. After the treatment of wet strip, the surface of DARC 14 will become hydrophilic because many hydrophilic functional groups such as OH, OOH and other functional groups are adhered onto the surface of DARC 14 after wash. The dry strip method, which uses oxygen plasma to remove first patterned photo-resist layer 18 and HMDS layer 16, also causes many pin holes on the surface of DARC 14, hence reducing the evenness thereof.
In the wake of the removal of first patterned photo-resist layer 18 and HMDS layer 16, the dry strip method forms another HMDS layer 26 on DARC 14 of FIG. 1C as shown in FIG. 1D through evaporation. Due to the adherence of hydrophilic functional groups other than OH functional group and OOH functional group onto the surface of DARC 14, HMDS layer 26 can only slightly reduce the hydrophilie on the surface of DARC 14. However, the surface of DARC 14 and HMDS 26 are still disposed to be hydrophilic, causing the adherence of the reworked patterned photo-resist layer to be reduced. Further due to the unevenness on the surface of DARC 14 or the remnants of acid agent contained in the pin holes thereon, the evenness on the surface of HMDS layer 26 formed on DARC 14 latter will be heavily influenced. When second patterned photo-resist layer 28 is formed on HMDS layer 26, the former can hardly be adhered onto the latter. Peeling will be easily experienced.